I recently put together an action to get all the positions along a Line Renderer curve as an Array of Vector3s, using LineRenderer.Getposition.

It's based on this Get Vertex Positions Action: http://hutonggames.com/playmakerforum/index.php?topic=3982

The yellow spheres here are having their positions set to each curve position every frame...

At the moment it cycling through the points and adding them to the array, there is a lineRenderer method to get them all at once which I assume would be much more efficient, but I couldn't get it to work!

I've also updated my Draw Curve actions to allow you to specify a Game Object variable for the Line renderer to make it easier to work with this action: http://hutonggames.com/playmakerforum/index.php?topic=11193.msg74970#msg74970